Method for preparing glyphosate by oxidizing N-(Phosphonomethyl)iminodiacetic acid with active carbon as catalyst oxygen

Abstract

The invention discloses a method for preparing glyphosate by taking active carbon as a catalyst and oxidizing N-(phosphonomethyl)iminodiacetic acid with oxygen. The method comprises the following steps: taking the active carbon which is made from coal, coconut shell and wood and has specific surface area of 800-1200m/g as the catalyst; oxidizing the N-(phosphonomethyl)iminodiacetic acid in the presence of the oxygen to prepare the glyphosate with reaction selectivity of 98% and 99% conversion of the N-(phosphonomethyl)iminodiacetic acid and solid glyphosate yield of 98.61-97.12% while producing a small amount of formaldehyde gas during the reaction; filtering after the reaction is over and then recovering the active carbon catalyst for indiscriminate use; supplementing 5% of the active carbon for each batch, wherein, the activity of the catalyst does not reduce after the oxidization reaction is repeated for 20 batches. The recovered catalyst and water can be repetitively used indiscriminately and recovered after the reaction without waste gas, waste water and waste residue. The method has the advantages of low material cost and convenient use.

Description

Technical field [0001] The invention relates to a method for preparing glyphosate, in particular to a method for preparing glyphosate by oxygen-oxidizing diglyphosate with activated carbon as a catalyst. Background technique [0002] Glyphosate (N-phosphonic acid methylglycine (PMG)) is a herbicide screened and synthesized by Monsanto Chemical Company in the 1960s, and belongs to amino acid derivatives. The good biological activity of glyphosate makes it a highly effective, low-toxic, post-emergence herbicide that is widely used. Its annual sales currently occupy the first place among pesticide products. Glyphosate is currently the pesticide with the largest output and sales volume in the world. Shuanglin is an important intermediate for the synthesis of glyphosate, and has a very broad international and domestic market. In recent years, glyphosate has been the world's largest pesticide sales, and global demand is expected to reach 1 million tons in 2010. [0003] The synthetic m...

AI Technical Summary

Problems solved by technology

[0015] At present, the most advanced technology for oxidizing N-phosphonomethyliminodiacetic acid into N-phosphonomethylglycine in the world is developed by Monsanto Company of the United States, such as the one disclosed in U.S. Patent Publication No. US2007 / 0100161A1. Activated carbon (AC) is loaded with precious metals (including platinum, palladium, rhodium, etc.) to oxidize N-phosphonomethyliminodiacetic acid to produce glyphosate under certain temperature, pressure and oxygen conditions, and the conversion rate of the reaction , The selectivity reaches 98%, but because the precious metal catalyst is expensive, there is about 0.2% loss in the recovery process after the reaction, and it is necessary to adopt a relatively complicated process and increase a large amount of equipment investment to recover this part of the lost precious metal. Compared with the selling price of glyphosate in the market, it is uneconomical in terms of cost

[0016] The disadvantages of these methods include several aspects: 1) the use of expensive noble metal catalysts makes it difficult to recover the catalysts, and the catalysts are easily lost; 2) the preparation methods of organic ligands are complicated, which increases the difficulty of product separation and purification

3) The catalyst needs to be replaced regularly; 4) There are patent restrictions

However, nano-activated carbon is inconvenient to use in terms of recovery, recycling and application in practical applications.

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